.\" -*- nroff -*-
.\" Copyright (c) 2010-2014 Cisco Systems, Inc.  All rights reserved.
.\" Copyright 2006-2008 Sun Microsystems, Inc.
.\" Copyright (c) 1996 Thinking Machines
.\" Copyright (c) 2020      Google, LLC. All rights reserved.
.\" $COPYRIGHT$
.TH MPI_Comm_delete_attr 3 "#OMPI_DATE#" "#PACKAGE_VERSION#" "#PACKAGE_NAME#"
.SH NAME
\fBMPI_Comm_delete_attr\fP \- Deletes attribute value associated with a key.

.SH SYNTAX
.ft R
.SH C Syntax
.nf
#include <mpi.h>
int MPI_Comm_delete_attr(MPI_Comm \fIcomm\fP, int \fIcomm_keyval\fP)

.fi
.SH Fortran Syntax
.nf
USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_COMM_DELETE_ATTR(\fICOMM, COMM_KEYVAL, IERROR\fP)
	INTEGER	\fICOMM, COMM_KEYVAL, IERROR \fP

.fi
.SH Fortran 2008 Syntax
.nf
USE mpi_f08
MPI_Comm_delete_attr(\fIcomm\fP, \fIcomm_keyval\fP, \fIierror\fP)
	TYPE(MPI_Comm), INTENT(IN) :: \fIcomm\fP
	INTEGER, INTENT(IN) :: \fIcomm_keyval\fP
	INTEGER, OPTIONAL, INTENT(OUT) :: \fIierror\fP

.fi
.SH INPUT/OUTPUT PARAMETER
.ft R
.TP 1i
comm
Communicator from which the attribute is deleted (handle).

.SH INPUT PARAMETER
.ft R
.TP 1i
comm_keyval
Key value (integer).

.SH OUTPUT PARAMETER
.ft R
.TP 1i
IERROR
Fortran only: Error status (integer).

.SH DESCRIPTION
.ft R
MPI_Comm_delete_attr deletes an attribute from cache by key. This function invokes the attribute delete function delete_fn specified when the \fIcomm_keyval\fP was created. The call will fail if the delete_fn function returns an error code other than MPI_SUCCESS.

Whenever a communicator is replicated using the function MPI_Comm_dup, all callback copy functions for attributes that are currently set are invoked (in arbitrary order). Whenever a communicator is deleted using the function MPI_Comm_free, all callback delete functions for attributes that are currently set are invoked.
.sp
This function is the same as MPI_Attr_delete but is needed to match the communicator-specific functions introduced in the MPI-2 standard. The use of MPI_Attr_delete is deprecated.


.SH NOTES
Note that it is not defined by the MPI standard what happens if the
delete_fn callback invokes other MPI functions.  In Open MPI, it is
not valid for delete_fn callbacks (or any of their children) to add or
delete attributes on the same object on which the delete_fn callback
is being invoked.


.SH ERRORS
Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument.
.sp
Before the error value is returned, the current MPI error handler is
called. By default, this error handler aborts the MPI job, except for I/O function errors. The error handler may be changed with MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned. Note that MPI does not guarantee that an MPI program can continue past an error.

